It is known in a rolling mill to brace one or both of the rolls in the respective stands by means of hydraulic adjustment mechanisms which are capable of exerting considerable force between the respective stand and the roller in a direction perpendicular to the roll rotation axis.
A standard such arrangement comprises a massive piston that is normally fixed on the traverse of the rolling-mill frame, and a cylinder surrounding this piston and engaged with the roll-carrying block. The chamber formed between this piston and its cylinder can be pressurized with a liquid under very high pressure so as to be able to exert the considerable force necessary in a rolling mill. Not only is the force with which the adjustment mechanism operates directly proportional to the pressure of the liquid, but in addition the speed with which the adjustment mechanism can operate is also proportional to this pressure.
The problem with these devices is that it is frequently necessary to exert a substantially reduced pressure, frequently only about 75% of the normal high pressure used. This is necessary when the rollers must not be urged together with too great a force. The disadvantage during this type of operation is, however, that adjustment speed is correspondingly reduced.